1. Field of the Invention
The present invention relates to a an automatic vacuum chuck that can pick and place a flexible sheet.
2. Background Information
Electronic assemblies sometimes incorporate flexible circuit boards to provide an interconnect between integrated circuits and/or integrated circuit packages. The flexible circuit boards may contain patterned conductive material located on opposite surfaces of a flexible dielectric substrate. It may be desirable to create vias in the dielectric material to connect the conductive material on one side of the dielectric substrate to the conductive material on the other side of the substrate. The vias are typically formed by initially creating holes in the substrate. The substrate is then placed in a plating bath to form the vias.
The dielectric material is typically supported by a worktable during the hole forming process. Each sheet of dielectric material can be automatically loaded onto the worktable from a tray full of dielectric sheets. The sheets are typically moved from the tray to the worktable by an automated vacuum chuck. The vacuum chuck may include a plurality of vacuum openings located within a flat metal surface. The vacuum openings pull an individual sheet out of the tray. The vacuum chuck then moves along a gantry to the worktable. The vacuum is terminated to allow the sheet to be placed onto the worktable.
It has been found that electrostatic forces and residual vacuum between the dielectric sheets may cause more than one sheet to be picked up by the vacuum chuck at a single time. The electrostatic forces may also cause the sheet to become misaligned on the chuck and the worktable. Additionally, the electrostatic forces increase the time required to pick up a sheet and thus reduce the amount of sheets per hour that can be processed. It would be desirable to provide a vacuum chuck that can more readily pick up and release a sheet than chucks of the prior art.
One embodiment of the present invention is an automated tool that can handle a sheet. The tool may include a flexible membrane that is attached to a frame. The flexible membrane may include a vacuum opening that is adapted to pull the sheet into the membrane.